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Standby power consumption measurement

Discussion in 'Misc Electronics' started by Jeff Layman, Apr 10, 2009.

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  1. Jeff Layman

    Jeff Layman Guest

    Given up trying to measure this on my LCD TV (egg see

    But could someone enlighten me as to how the TV manufacturers do it? What
    type of equipment would they use to measure these low consumptions from
    power supplies using (very) irregular waveforms?
  2. Don Stauffer

    Don Stauffer Guest

    I don't think they worry very much about irregular waveforms. I think
    they pretty much assume you will be using it on normal power grid. So a
    regular wattmeter or equivalent would be okay. Or, an AC ammeter, since
    they know the voltage reasonably well.

    I also feel my manual will give me a reasonable value- why should they
    lie? My manual indicated my LCD TV has a negligible consumption when
    off, not the monster drains that some news broadcasts have touted.
  3. Jeff Layman

    Jeff Layman Guest

    According to the forum thread I quoted, ordinary instruments do not give an
    accurate measurement of power consumption with standby power levels. I
    don't understand the technicalities (power factors, pulsed voltages, etc) as
    they seems to give pretty accurate readings when the TVs are operating

    And as to the figure quoted in the manual, not everything is as it seems ;-)
  4. Eeyore

    Eeyore Guest

    Things called true power meters.

  5. Eeyore

    Eeyore Guest

  6. Eeyore

    Eeyore Guest

    Or operating quite often too.

    Read my reply.

  7. News123

    News123 Guest

    What I consider strange is:
    Though I agree with:
    I must say, that it's not only Sony's fault.
    If the government distributes 'Energy Star' stickers, then they should
    have cwertification / measuring techniques, which capture such issues.
    As more and more devices are doing things like auto updates and other
    nanny work while officially being switched off, they might have to
    increase the time, they take for measuring.
  8. Eeyore

    Eeyore Guest

    Standby power consumption is increasingly having limits mandated by the IEC ( International Electrotechnical Commission ). Having standards that only apply in one country is rather silly.

    The current goal AIUI is to get consumer goods down to 1W in standby. That's not ratified yet. Instead we have silly set-top boxes like the one supplied by my cable co that apparently does nothing other than blank the display
    when put in standy and consumes the same power more or less.

    My CRT monitor does drop to 3W in standby though ( Sony 21" E530 ) which I reckon is pretty good. 130W active.

  9. Don Stauffer

    Don Stauffer Guest

    But how much of a power factor does a modern piece of electronics have?
    Yeah, a motor or something with a very large inductor has a lot, but
    from what I have seen from the guts of modern heavy IC electronics,
    there isn't much in there to create a big power factor. No big
    deflection coils and stuff like that any more. Big enormous filter caps
    seem to have disappeared.
  10. Jeff Layman

    Jeff Layman Guest


    But Google not much help here - only 39 hits for "true power meter", and
    many of those completely irrelevant.

    Found one link which led to a Fluke 43B, but that cannot go down to 0.3w.
    Most of the relevant refs were for higher power measurement (eg those which
    could check house electricity meters). Other delving for lower power
    instruments only turned up those for RF power measurement.

    Could you point me in the direction of an instrument which measures powers
    below 1w at 50Hz, or suggest other suitable search terms?

  11. Ken

    Ken Guest

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